Mp3 timing different than audacity file!`

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Mp3 timing different than audacity file!`

Permanent link to this post Posted by violetdreamer » Sun Jul 16, 2017 2:48 pm

I'm using Auduacity 2.1.3
and I'm on Windows 8.1 Pro

Issue: The audacity file and the MP3 file that I export directly from it times don't match up. It's a podcast, I'm trying to mark certain times during the podcast that things happen, the file length stays the same but the min:sec don't match up. I can't figure out why or what I'm doing wrong.
I just tested this, opened the audicity file I was working on, exported an Mp3 directly from it, The lengths are the same but when I go to the same time in audacity that I want in the mp3 they are different, off by about 10 seconds or so
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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by kozikowski » Sun Jul 16, 2017 3:00 pm

The standard reply to questions like this is stop doing production in MP3. MP3 has built-in timing errors and is never going to match lip-sync or timing production. But not off by 10 seconds.
The lengths are the same

I bet the lengths are not the same, but not off by that much.

How long is the show? Two hours? Three hours?

Who's ahead? Does the produced MP3 always arrive late? Does the produced MP3 start and stop right? What kind of content is it?

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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by steve » Sun Jul 16, 2017 5:35 pm

violetdreamer wrote:The lengths are the same but when I go to the same time in audacity that I want in the mp3 they are different, off by about 10 seconds or so

What is the program that you are playing the MP3 in?
I bet that if you open the MP3 in Audacity, the timings will be off by no more than a small fraction of a second (that small fraction is due to a limitation of the MP3 format).

Some programs have problems reporting the correct time for MP3s when the MP3s are encoded with variable bit-rate ("VBR"). By default, Audacity uses VBR for MP3 as VBR gives better sound quality than CBR (constant bit rate) for the same file size.

If your "other" application can't handle timings for VBR correctly, you could either (a) use a better application that does not have the problem, or (b) Select "Constant" as the bit-rate mode in Audacity's export dialog. (see: http://manual.audacityteam.org/man/mp3_ ... tions.html)
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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by kozikowski » Sun Jul 16, 2017 7:20 pm

My fuzzy, right-brain impression is that the show matches beginning and end, but it's significantly off in the middle. That's almost impossible which is why a simple answer doesn't leap out.

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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by violetdreamer » Mon Jul 17, 2017 6:46 pm

Hi, thanks for the help
I've been using windows media player and now I'm using VLC media player. I double checked, the times are the same.
I am new at this, the content is just talking and begins /ends with a music/talk intro that I've copied in.

The Audacity file is later than then MP3 file.
I'm using MP3 because I thought that was best for a podcast. I am open to other suggestions. This podcast will be uploaded to a website and then played directly from there. I am unsure of the format but if it's important I can find out.

I checked this again using VLC this time instead of WMP and it's only 3 seconds off, which isn't a big deal. I guess my concern is that once I do all the work and we post it online it's going to be off by 10 seconds or so and I would like to avoid that. It's important to me that the timing at the very least matches the mp3 that I'm turning in !
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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by violetdreamer » Mon Jul 17, 2017 6:48 pm

The show lengths vary from about 35 to 45 minutes
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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by steve » Tue Jul 18, 2017 12:03 am

For voice only podcast, it is generally recommended to use mono, 96 kbps, CBR, MP3. Encoding should be the final step in the production - use WAV format whenever possible during the production stages, then export as MP3 as the final step (plus a WAV format backup copy).
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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by kozikowski » Tue Jul 18, 2017 12:37 am

I'm using MP3 because I thought that was best for a podcast.

It's best for posting, not for production. Each time you make a change to an MP3, the quality takes a hit.

The show lengths vary from about 35 to 45 minutes

Cool. Say a 40 minute show. You do the Performance however you want—interviews, chatting with the neighbor's cat—and Export that as a WAV (but leave it on the timeline).

This is the time you make corrections and filtering and effects, etc, etc, etc. I'm assuming a perfect conversation with the cat.

That comes out to 39:30. You produce the :15 introduction (if you don't already have it prepared) and the :15 Outro. Open them on their own tracks. Use the Time Shift Tool to push the Performance to the right so it starts at the exact instant the Intro stops. Then you Time Shift Tool the Outro to the right until it starts when the Performance stops.

When you play this, the show will appear absolutely correct since Audacity will play all the tracks unless you stop the playback with the MUTE and SOLO buttons. First the Intro on track 2 plays, then the show on track 1, then the Outro on track 3.

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Export the Final Master WAV and if you do nothing else, Audacity will jam all the tracks together into one show. Only then do you go back and Export the MP3 using Steve's info as the model for posting.

Yes, I know the example is mono instead of stereo and the times are all wrong. It's just to illustrate the philosophy of editing. Where did that part company with what you're doing?

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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by kozikowski » Tue Jul 18, 2017 12:48 am

I'm no editing genius. That's only one way to do it, but if you have a simple podcast, it may be the simplest way. Note that first WAV you made when you got done with the cat? Save That WAV on a separate thumb drive or safe place and Do Not change it. Edit and correct a copy of that file.

If your show edit flushes itself into the mud by computer failure or fatal mistake, you will not have to interview the cat again. Just open the protection copy and keep going (after you fix the computer).

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Re: Mp3 timing different than audacity file!`

Permanent link to this post Posted by kozikowski » Tue Jul 18, 2017 12:53 am

Also note nowhere in this did we advocate Saving an Audacity Project. You need that if you wanted to save the step where you had all the tracks one above the other. Projects can do that. But Projects can be brittle and hard to understand. Export the WAV files anyway and then the Project in addition if you want to.

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